Tips, tricks & notes:

•The Lunar Spellbook is useful, since it offers teleports to Lunar Isle and Waterbirth Island. When you need to change to the Standard Spellbook for the boss fight, simply pray at the Astral Altar on Lunar Isle.
•The fight against the Dagannoth Mother is inventory-intensive, as it requires the use of various runes and other items. It is therefore suggested to use a Beast of Burden familiar to carry additional supplies for you (food in particular).
•Bank while you can! You'll often be forced into time-consuming combat situations during the quest which can quickly drain you of supplies. Restock at every opportunity you receive, particularly whenever Brundt gives you the option to bank at Etceteria.
•The Prophecy tablets, while discussed throughout the quest, are NOT required items; there is no need to carry them in order to advance through the quest.